Regional authorities reported the reading, which needs to be verified by the World Meteorological Organization (WMO), near Syracuse on Wednesday.
According to the WMO, the current official record in Europe is 48C, registered in Athens, Greece, in 1977.
The latest heatwave in Italy is being caused by an anticyclone - nicknamed Lucifer - moving up from Africa.
Anticyclones are areas of high atmospheric pressure where the air is sinking.
Lucifer is forecast to head north across mainland Italy, further raising temperatures in cities including the capital, Rome.